There are many medical treatments and diagnostic procedures the efficacy of which can be improved by coordinating such treatment or procedure with a patient""s physiological cycles, for example a patient""s breathing cycle. In many instances patients can control their breathing to assist the medical provider. However, some patients are not able to control their breathing, for example patients on ventilators. Other physiological cycles, for example the beating of a patient""s heart, are typically out of the patient""s control entirely. Accordingly, an apparatus which could facilitate the timing of such a medical treatment or a diagnostic procedure with respect to one or more physiological cycles of a patient would be beneficial to the patient.
As an example, chest radiographs are often taken in the intensive care unit using portable x-ray machines. These x-ray images provide important information to the clinician and, therefore, the quality of the images is important. Factors which can affect the quality of chest radiographs include: patient position and movement; ability of patient to receive and respond to instruction; penetration of the x-ray beam; and, perhaps most important, timing of the x-ray beam exposure with patient insufflation.
Typically, the highest quality chest images are attained when the image is taken at peak insufflation because there is less tissue mass per unit area, and penetration is uniform. Accordingly, patients who are able to receive and respond to instruction can be instructed to take and hold a deep breath long enough to take the required images, for example radiographs. However, for patients on a ventilator, in order to take the radiograph at peak insufflation, the person taking the radiograph must attempt to accurately time the x-ray beam exposure with the cycle of the ventilator. When the radiograph is not timed correctly, it may be less than optimal and additional costs are incurred if it is necessary to retake the radiograph. Furthermore if time is critical, the caregiver may be forced to provide care with inadequate information.
Current techniques for synchronizing the x-ray beam exposure with peak lung inflation (PLI) include placing a paper cup on the chest of a supine patient and visually anticipating PLI. This results in variable radiograph quality and the frequent need for repeat radiographs, which increases radiation exposure to the patient, personnel and material costs, delays in initiating treatment, and reduced confidence in the diagnostic information contained in the radiograph.
With respect to magnetic resonance imaging (MRI) images, a plurality of images often need to be taken of adjacent slices of the patient. When imaging parts of the body where the motion of the patient, for example due to the patient""s breathing, can affect the quality of the images, care needs to be taken such that images of adjacent slices are taken with as little motion of the body between images as possible. Prior techniques for effecting MRI images of a patient""s thorax and upper abdomen region have included respiratory gating (Ehman et al (December 1994) xe2x80x9cMagnetic Resonance Imaging with Respiratory Gating: Techniques and Advantagesxe2x80x9d AJR: 143).
Accordingly, there exists a need in the art for a method and device which can ensure that chest images of patients on ventilators are taken at a desired degree of insufflation to enhance the quality of such chest images. These images can be effected by a variety of apparatus, including but not limited to, MRI machines, CAT scan machines, and PET scan machines. In particular, a device which could interface a ventilator with an x-ray machine to ensure chest radiographs are taken at peak ventilation would improve the quality of such chest radiographs and, therefore, improve the quality of care for ventilated patients.
Additional situations where the efficacy of the medical treatment or procedure can be affected by timing the treatment or procedure with respect to a desired point in the breathing cycle include, but are not limited to, inhalation therapy, oxygen (O2) delivery, cardiac output (CO) measurements, blood pressure measurements, and pulse oximeter optoplethysmograms. With inhalation therapy and O2 delivery, timing the delivery of the appropriate substances with respect to the breathing cycle can affect the dose administered, the amount of waste, pollution, and costs. With blood pressure measurements, CO measurements, and pulse oximeter optoplethysmograms, the timing of the measurements with respect to the breathing cycle can affect, for example, the precision of the readings.
Accordingly, there exists a need in the art for a method and device which can coordinate a medical treatment or diagnostic procedure with respect to one or more physiological cycles of a patient in order to enhance the efficacy of the medical treatment or diagnostic procedure.
The subject invention pertains to a method and apparatus for coordinating a medical treatment or diagnostic breath procedure with respect to one or more physiological cycles of a patient. The subject invention is applicable to human or animal patients. In a specific embodiment, the subject invention pertains to a novel method of coordinating a chest radiograph with the ventilatory cycle. In another specific embodiment, the subject invention relates to a novel method of coordinating a medical treatment or diagnostic procedure with the pumping of the patient""s heart, for example in order to remove artifacts produced by the pumping of the heart.
The methods and apparatus of the subject invention are particularly advantageous for use in chest radiography. In a specific example, the subject invention concerns a novel device for interfacing a ventilator and an x-ray machine to ensure that an x-ray chest image can be taken at a desired degree of ventilation of the patient, for example, peak lung inflation. The interfacing of a ventilator and an x-ray machine, according to the subject invention, improves the chest image quality and, therefore, improves the quality of medical care received by the patient. In a specific embodiment, the taking of a radiograph can be accomplished by emulating an x-ray machine firing handle with software, for example, on a notebook personal computer. In a preferred embodiment, the subject invention utilizes a standard firing handle currently used with x-ray machines, in order to minimize the retraining required by operators. The use of the standard firing handle in accordance with the subject invention can be made to mimic its current use with the exception that instead of the operator attempting to time an event with the ventilatory cycle, software controls the timing of such event.
Further embodiments of the subject invention pertain to, for example, the delivery of inhalants, delivery of oxygen (O2), blood pressure measurements, cardiac output (CO) measurements, pulse oximeter optoplethysgrams, and further imaging techniques. With respect to the delivery of inhalants and the delivery of O2, the method and apparatus of the subject invention can improve the efficiency of the delivery of the appropriate substance, improve the accuracy of administering the correct dose, and reduce waste and costs. With respect to blood pressure measurements, CO measurements and pulse oximeter optoplethysgrams, the method and apparatus of the subject invention can improve the precision and consistency of the measurements by timing the measurements with respect to the breathing cycle of a patient.